The 2320 Starr Edwards aortic valve has a composite seat with metallic studs protruding through the cloth. Six patients who had this prosthesis in situ for 50-144 months (mean 92) had considerable disruption of the cloth covering both struts and base, and varying degrees of wear of the metallic studs lining the luminal side of the prosthetic ring. The cloth covering the luminal side of the ring was proportionally more disrupted than was the cloth covering the 3 struts. Part of the wear of the cloth covering the ring resulted from wear of the metallic studs by the poppet during ventricular diastole allowing the metallic poppet to contact directly the metallic ring. Excessive stud wear in this circumstance always results in severe disruption of the cloth lining the interior of the prosthetic ring. The disrupted cloth may lead to hemolytic anemia and to emolic consequences. Of our 6 patients, 4 had severe hemolytic anemia, 4 had neurologic events compatible with emboli and 1 died suddenly. Stud wear as observed in the 2320 series Starr-Edwards prosthesis also may occur in the models 2310 and 2400 prostheses which have the same composite seat.